The superplasticity improvement of Inconel 718 through grain refinement by large reduction cold rolling and two-stage annealing

In this work, the influence of thermal (TT), mechanical, and thermomechanical (TMT) treatments using the ultrasonic nanocrystal surface modification (UNSM) on the corrosion protection properties of Inconel 718 was studied, correlating the changes in the electrochemical properties with the promoted microstructure. The UNSM treatment had a grain refinement effect on the top surface, reducing the grain size from 11.5 to 7.4 µm for the first 10 µm in depth. The high grain boundary density, due to the grain refinement, enabled a faster growth of the passive film. The impedance showed a decrease in the charge transfer resistance by three orders of magnitude, from 106 to 103 Ω cm2 for as-received to 1000 °C, as the TT temperature crossed the solvus of the γ′/γ″ and approached the solvus of the δ-phase. The UNSM treatment lowered the pitting corrosion susceptibility, increasing the charge transfer resistance and decreasing the effective capacitance of the double layer, leading to the thickest passive film with 6.8 nm.

Download Full-text

Ultrathin-gauge high silicon non-oriented electrical steel with high permeability and low core loss fabricated by optimized two-stage cold rolling method

Materials Characterization ◽

10.1016/j.matchar.2021.111593 ◽

2021 ◽

pp. 111593

Author(s):

Zhi-hong Li ◽

Song-kang Xie ◽

Guo-dong Wang ◽

Hai-tao Liu

Keyword(s):

Cold Rolling ◽

Electrical Steel ◽

Core Loss ◽

High Permeability ◽

Two Stage ◽

Rolling Method ◽

High Silicon

Download Full-text

Grain refinement and mechanical properties improvement of AZ31 Mg alloy sheet obtained by two - stage rolling

Materials Science and Engineering A ◽

10.1016/j.msea.2017.02.107 ◽

2017 ◽

Vol 691 ◽

pp. 81-87 ◽

Cited By ~ 21

Author(s):

Ru Ma ◽

Yiquan Zhao ◽

Yinong Wang

Keyword(s):

Mechanical Properties ◽

Grain Refinement ◽

Alloy Sheet ◽

Mg Alloy ◽

Two Stage ◽

Az31 Mg Alloy

Download Full-text

UFG to NC FePd by Combined Reaction Transformation Mode of Severely Plastically Deformed Disordered FePd

MRS Proceedings ◽

10.1557/proc-980-0980-ii05-18 ◽

2006 ◽

Vol 980 ◽

Author(s):

Vincent Sokalski ◽

Andreas Kulovits ◽

Jorg Wiezorek

Keyword(s):

Grain Size ◽

Magnetic Properties ◽

Phase Transformation ◽

Cold Rolling ◽

Grain Refinement ◽

Magnetization Curve ◽

Deformation Process ◽

Intermetallic Alloys ◽

Fine Grained ◽

Angular Pressing

AbstractNumerous studies have shown that equiaxed ultra fine grained FePd alloys can be produced by phase transformation of heavily deformed austenitic FePd via the combined reaction mode. As the magnetic properties can be improved by suppression of the polytwinned micro-constituent formed by the conventional ordering mode it appears reasonable to speculate that further grain refinement might lead to further enhancement. In order to reduce the grain size in bulk intermetallic alloys severely plastically deformed austenitic FePd has been phase transformed in this study. Equal channel angular pressing (ECAP) has been used to deform disordered FePd. The microstructure and property evolution during the deformation process and post-deformation annealing have been studied using SEM, TEM and hardness and magnetization curve measurements. The observations are compared to known results from use of other deformation processing routes, such as cold rolling.

Download Full-text